Alkenyl compound having a negative delta epsilon value, liquid crystal composition, and liquid crystal display device

ABSTRACT

There are provided a liquid crystalline compound having a large negative Δε, low viscosity, a large K 33 /K 11  value, a small Δε/εL and mutually excellent solubility even at extremely low temperature; a liquid crystal composition prepared from a liquid crystalline compound; and a liquid crystal display device fabricated from such a liquid crystal composition. The liquid crystalline compound of the present invention is a liquid crystalline compound represented by the following general formula (1):  
                 
 
     where, R 1  represents hydrogen, fluorine, an alkyl group having 1 to 15 carbon atoms, or an alkenyl group having 2 to 15 carbon atoms; each of rings A 1 , A 2 , and A 3  independently represents trans-1,4-cyclohexylene group, 1,4-cyclohexenylene group, trans-1,4-silacyclohexylene group, 1,4-phenylenegroup, 2,3-difluoro-1,4-phenylene group, 2-fluoro-1,4-phenylene group, 3-fluoro-1,4-phenylene group, pyrimidine-2,5-diyl group, pyridine-2,5-diyl group, 1,3-dioxane-2,5-diyl group, tetrahydropyrane-2,5-diyl group, 1,3-dithiane-2,5-diyl group, or tetrahydrothiopyrane-2,5-diyl group; X 1  represents hydrogen or fluorine; Y 1  represents hydrogen or an alkyl group having 1 to 15 carbon atoms; 1 represents an integer from 1 to 10; and each of m and n independently represents 0 or 1.

TECHNICAL FIELD

[0001] The present invention relates to a liquid crystalline compoundand a liquid crystal composition, and more particularly, to a novelliquid crystalline compound simultaneously having an alkenyl group and2,3-difluorophenyl group, a liquid crystal composition containing such acompound, and a liquid crystal display device constituted from such aliquid crystal composition.

BACKGROUND ART

[0002] When a voltage is impressed to a conventional TN mode TFT displayor a conventional STN display, liquid crystal molecules rotate to extendin the direction perpendicular to the substrate. When such liquidcrystal molecules rise diagonally (i.e., such that they extendperpendicular to the substrate), there arise problems in that theoptical properties of the liquid crystal molecules differ depending onthe angle from which the liquid crystal panel is viewed, and in that theview angle is narrow.

[0003] As systems for realizing a wide view angle, theIn-Plane-Switching (IPS) system characterized in the formation of combstyle electrodes on one substrate (G. Baur, Freiburger ArbeistagungFlussigkristalle, Abstract No. 22 (1993), M. Oh-e, et al., ASIA DISPLAY'95, 577 (1995)), and the Vertically Aligned (VA) system (K. Ohmuro, etal., SID 97 DIGEST, 845 (1997)) have attracted attention, and have beenput into practical use.

[0004] In the IPS system, since liquid crystal molecules rotate withinthe surface plane of the glass substrate, the view angle is greatlywidened. In the VA system, liquid crystal molecules rotate from thevertical direction to the horizontal direction to the substrate, and awide view angle is realized by controlling orientation in a kind ofmulti-domain system.

[0005] However, as compared to CRTs, these display systems still haveproblems, and there are the demands for improvement of response time,improvement of contrast, and decrease of driving voltage.

[0006] The liquid crystalline compound employed in IPS and VA systemsmust have the large negative value of dielectric anisotropy (Δε) for itsdisplay properties, and a low viscosity for improving response time.Since active matrix driving is utilized as the driving method, thecompound must have a high voltage holding ratio (V.H.R.) in order toimprove contrast.

[0007] Various compounds have been known to have negative values ofdielectric anisotropy, and the following compounds (a) and (b) aredisclosed in Japanese Patent Application Laid Open No. 2-4725 andJapanese-translated PCT Patent Application Laid-open No. 2-503441:

[0008] Where, R′ represents an alkyl group or an alkoxy group.

[0009] Although each of the above liquid crystalline compounds, (a) and(b), has 2,3-difluoro-1,4-phenylene group as part of its structure, andhas a negative Δε, |Δε| is not sufficiently large and viscosity is high.Furthermore, mutually good solubility its with other liquid crystallinecompounds, especially mutually good solubility at very low temperature,is not sufficiently high, and a liquid crystal composition containingsuch compounds is so unstable that low-temperature storage results inprecipitation of crystals or appearance of a smectic phase.

[0010] In order to solve the problems involved in the prior arttechniques, an object of the present invention is to provide a liquidcrystalline compound having a wide temperature range within which aliquid crystal phase exists (hereinafter called a “liquid crystal phasetemperature range”), a large negative As, low viscosity, and mutuallygood solubility at low temperature, which can contribute to improvingresponse time and contrast and lowering driving voltage in IPS and VAsystems and can contribute to improving steepness of the V-T(voltage-transmissivity) curve and contrast by increasing the K₃₃/K₁₁value in the STN system; a liquid crystal composition containing suchliquid crystalline compounds, and a liquid crystal display deviceconstituted from such a liquid crystal composition.

DISCLOSURE OF INVENTION

[0011] The present inventors conducted repeated examinations forachieving the above and other objects, and found that each of a group ofcompounds containing an alkenyl group and 2,3-difluoro-1,4-phenylenegroup, represented by formula (1), exhibits a large negative Δε, wideliquid crystal phase temperature range, low viscosity, and mutuallyexcellent solubility at low temperature, and that Δε/ε⊥, can bedecreased and the K₃₃/K₁₁ value can be increased by appropriateselection of the positions of double bonds in the alkenyl group toattain the present invention.

[0012] The present invention is described as follows.

[0013] According to a first aspect of the present invention, there isprovided a liquid crystalline compound represented by the followinggeneral formula (1):

[0014] where, R¹ represents hydrogen, fluorine, an alkyl group having 1to 15 carbon atoms, or an alkenyl group having 2 to 15 carbon atoms;each of rings A¹, A² and A³ independently representstrans-1,4-cyclohexylene group, 1,4-cyclohexenylene group,trans-1,4-silacyclohexylene group, 1,4-phenylene group,2,3-difluoro-1,4-phenylene group, 2-fluoro-1,4-phenylene group,3-fluoro-1,4-phenylene group, pyrimidine-2,5-diyl group,pyridine-2,5-diyl group, 1,3-dioxane-2,5-diyl group,tetrahydropyrane-2,5-diyl group, 1,3-dithiane-2,5-diyl group ortetrahydrothiopyrane-2,5-diyl group; X¹ represents hydrogen or fluorine;Yl represents hydrogen or an alkyl group having 1 to 15 carbon atoms, inwhich each of optional nonadjacent methylene groups (—CH₂—) may besubstituted by oxygen; 1 represents an integer from 1 to 10; in whicheach of optional nonadjacent methylene groups in (—CH₂—)₁ may besubstituted by oxygen; and each of m and n independently represents 0 or1.

[0015] According to a second aspect of the present invention, there isprovided a liquid crystalline compound according to the first aspect,wherein the ring A₁ in the general formula (1) istrans-1,4-cyclohexylene group and m and n are both 0.

[0016] According to a third aspect of the present invention, there isprovided a liquid crystalline compound according to the first aspect,wherein each of the rings A¹ and A² in general formula (1) isindependently trans-1,4-cyclohexylene group, 2,3-difluoro-1,4-phenylenegroup or 1,3-dioxane-2,5-diyl group; m is 1; and n is 0.

[0017] According to a fourth aspect of the present invention, there isprovided a liquid crystalline compound according to the first aspect,wherein each of the rings A¹, A² and A in general formula (1) isindependently trans-1,4-cyclohexylene group, 2,3-difluoro-1,4-phenylenegroup or 1,3-dioxane-2,5-diyl group; and m and n are both 1.

[0018] According to a fifth aspect of the present invention, there isprovided a liquid crystal composition comprising at least twocomponents, characterized by containing at least one liquid crystallinecompound represented by general formula (1).

[0019] According to a sixth aspect of the present invention, there isprovided a liquid crystal composition comprising at least one liquidcrystalline compound according to any of the first through fourthaspects as a first component and at least one compound selected from agroup consisting of compounds represented by general formulas (2), (3)and (4) as a second component,

[0020] where R² represents an alkyl group having 1 to 10 carbon atoms,in which each of optional nonadjacent methylene groups may besubstituted by oxygen or —CH═CH— group, and in which each of optionalhydrogen in these methylene groups may be substituted by fluorine; Y²represents fluorine, chlorine, —OCF₃, —OCF₂H, —CF₃, —CF₂H, —CFH₂,—OCF₂CF₂H or —OCF₂CFHCF₃; each of L¹ and L² independently representshydrogen or fluorine; each of Z¹ and Z² independently represents1,2-ethylene group, vinylene group, 1,4-butylene group, —COO—, —CF₂O—,—OCF₂— or a single bond; ring B represents trans-1,4-cyclohexylenegroup, 1,3-dioxane-2,5-diyl group or 1,4-phenylene group, in which eachof hydrogen may be substituted by fluorine; and ring C representstrans-1,4-cyclohexylene group or 1,4-phenylene group, in which each ofhydrogen may be substituted by fluorine.

[0021] According to a seventh aspect of the present invention, there isprovided a liquid crystal composition comprising at least one liquidcrystalline compound according to any of the first through fourthaspects as a first component, and at least one compound selected from agroup consisting of compounds represented by general formulas (5) and(6) as a second component,

[0022] where each of R³ and R⁴ independently represents an alkyl grouphaving 1 to 10 carbon atoms, in which each of optional nonadjacentmethylene groups may be substituted by oxygen or vinylene group, and inwhich each of optional hydrogen in these methylene groups may besubstituted by fluorine; Y³ represents —CN or —C≡C—CN; ring D representstrans-1,4-cyclohexylene group, 1,4-phenylene group, pyrimidine-2,5-diylgroup or 1,3-dioxane-2,5-diyl group; ring E representstrans-1,4-cyclohexylene group or 1,4-phenylene group, in which each ofoptional hydrogen may be substituted by fluorine; or pyrimidine-2,5-diylgroup; ring F represents trans-1,4-cyclohexylene group or 1,4-phenylenegroup; Z³ represents 1,2-ethylene group, —COO— or a single bond; each ofL³, L⁴ and L⁵ independently represents hydrogen or fluorine; and each ofa, b and c independently represents 0 or 1.

[0023] According to an eighth aspect of the present invention, there isprovided a liquid crystal composition comprising at least one liquidcrystalline compound according to any of the first through fourthaspects as a first component and at least one compound selected from agroup consisting of compounds represented by general formulas (7), (8)and (9) as a second component,

[0024] where each of R⁵ and R⁶ independently represents an alkyl grouphaving 1 to 10 carbon atoms, in which each of optional nonadjacentmethylene groups may be substituted by oxygen or vinylene group and inwhich each of optional hydrogen in these methylene groups may besubstituted by fluorine; each of rings G, I and J independentlyrepresents trans-1,4-cyclohexylene group, pyrimidine-2,5-diyl group or1,4-phenylene group in which hydrogen may be substituted by fluorine;and each of Z⁴ and Z⁵ independently represents 1,2-ethylene group,vinylene group, —COO—, —C≡C— or a single bond.

[0025] According to a ninth aspect of the present invention, there isprovided a liquid crystal composition comprising at least one liquidcrystalline compound according to any of the first through fourthaspects as a first component and at least one compound selected from agroup consisting of compounds represented by general formulas (10), (11)and (12) as a second component,

[0026] where each of R⁷ and R⁸ independently represents an alkyl grouphaving 1 to 10 carbon atoms, in which each of optional nonadjacentmethylene groups may be substituted by oxygen or vinylene group, and inwhich each of optional hydrogen in these methylene groups may besubstituted by fluorine; each of rings K and M independently representstrans-1,4-cyclohexylene group or 1,4-phenylene group; each of L⁶ and L⁷independently represents hydrogen or fluorine, but L⁶ and L⁷ are notboth hydrogen simultaneously; and each of Z⁶ and Z⁷ independentlyrepresents —CH₂CH₂—, —CH₂O— or a single bond.

[0027] According to a tenth aspect of the present invention, there isprovided a liquid crystal composition comprising at least one liquidcrystalline compound according to any of the first through fourthaspects as a first component, at least one compound selected from agroup consisting of compounds represented by general formulas (7), (8)and (9) as a second component and at least one compound selected from agroup consisting of compounds represented by general formulas (10), (11)and (12) as a third component.

[0028] According to an eleventh aspect of the present invention, thereis provided a liquid crystal composition comprising at least one liquidcrystalline compound according to any of the first through fourthaspects as a first component, at least one compound selected from agroup consisting of compounds represented by general formulas (2), (3)and (4) as a second component and at least one compound selected from agroup consisting of compounds represented by general formulas (7), (8)and (9) as a third component.

[0029] According to a twelfth aspect of the present invention, there isprovided a liquid crystal composition comprising at least one liquidcrystalline compound according to any of the first through fourthaspects as a first component, at least one compound selected from agroup consisting of compounds represented by general formulas (5) and(6) as a second component and at least one compound selected from agroup consisting of compounds represented by general formulas (7), (8)and (9) as a third component.

[0030] According to a thirteenth aspect of the present invention, thereis provided a liquid crystal composition comprising at least one liquidcrystalline compound according to any of the first through fourthaspects as a first component, at least one compound selected from agroup consisting of compounds represented by general formulas (2), (3)and (4) as a second component, at least one compound selected from agroup consisting of compounds represented by general formulas (5) and(6) as a third component, and at least one compound selected from agroup consisting of compounds represented by general formulas (7), (8)and (9) as a fourth component.

[0031] According to a fourteenth aspect of the present invention, thereis provided a liquid crystal composition according to any of the fifththrough thirteenth aspects further comprising one or more opticallyactive compounds.

[0032] According to a fifteenth aspect of the present invention, thereis provided a liquid crystal display device constituted from a liquidcrystal composition according to any of the fifth through fourteenthaspects.

[0033] The liquid crystalline compounds of the present inventionrepresented by the general formula (1) are compounds having two to fourrings and characterized by containing an alkenyl group and2,3-difluorophenyl group simultaneously. These liquid crystallinecompounds not only exhibit physical and chemical stability underconditions where liquid crystal display devices are used, but also havea wide liquid crystal phase temperature range, a large negative As, andlow viscosity, enable an increase in the K₃₃/K₁₁ value, and are highlysoluble in liquid crystal compositions even at low temperature.

[0034] Although, as described in the description of the Background Art,compounds having 2,3-difluoro-1,4-phenylene group in respective partialstructures have been disclosed in patent gazettes or other references,the present inventors are the first to discover that compounds havingboth an alkenyl group and the above structure have the above features.In the compounds of the present invention, desired properties can beadjusted by suitable selection of the ring structures, or the structuresof bonding groups or side chains among the elements constituting amolecule. Therefore, when the compounds of the present invention ateused as the components of liquid crystal compositions, nemetic liquidcrystal compositions having the following preferable properties can beprepared.

[0035] 1) Since the liquid crystal phase temperature range is wide, theusable temperature range is expanded.

[0036] 2) Since the compositions have large negative Δε and lowviscosity, response time is improved and driving voltage is lowered inIPS and VA systems. 3) Since the K₃34K₁₁ value can be increased andΔε/ε⊥ can be decreased in the STN system, the steepness of the V-T(voltage-transmissivity) curve is improved.

[0037] 4) Stable nematic liquid crystal compositions can be preparedwithout the precipitation of crystals and the appearance of a smecticphase, even at extremely low temperature.

[0038] Thus, there can be provided novel liquid crystal compositions andliquid crystal display devices which are stable in usage environments,which realize the expansion of usable temperature range, and which havea low driving voltage and high response speed and provide high contrast.

[0039] Although all compounds of the present invention have favorableproperties, a liquid crystal composition meeting the requirements ofspecific applications can be prepared by use of compounds in which R¹,ring A¹, ring A², ring A³, X¹, Y¹, l, m and n in general formula (1)have been properly selected.

[0040] If a compound having a large negative Δε is desired,2,3-difluoro-1,4-phenylene group may be bonded at the site of ring A¹,ring A², or ring A³; if the liquid crystal phase temperature range isrequired to be on the low-temperature side, a two-ring compound (m=n=04)may be selected; if the liquid crystal phase temperature range isrequired to be on the high-temperature side, a three-ring or four-ringcompound (m+n=1 or m+n=2) may be selected; and if a large refractiveindex of anisotropy is required, 1,4-phenylene group may be bonded atthe site of ring A¹, ring A² or ring A³. The compound in which ahydrogen atom on the 1,4-phenylene group is substituted by a fluorineatom has especially excellent solubility at low temperature.

[0041] Among the compounds represented by the general formula (1),examples of especially favorable compounds are those represented by thefollowing general formulas (1-1) through (1-7):

[0042] where, ring A¹, ring A², ring A³, and Y¹ have the same meaningsas described above, and R has the following structure;

[0043] where, R¹ and X¹ have the same meanings as described above.

[0044] In general formulas (1-1) through (1-7), R represents an alkenylgroup or an alkenyloxy group having 2 to 15 carbon atoms, among whichvinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl,1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 2-propenyloxy,2-butenyloxy, 2-pentenyloxy and 4-pentenyloxy groups are particularlypreferable; and Y¹ represents hydrogen, an alkyl group having 1 to 15carbon atoms or an alkoxy group, among which methyl, ethyl, propyl,butyl, pentyl, hexyl, heptyl, octyl, methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, and octyloxy groups are particularlypreferable.

[0045] The liquid crystal composition of the present invention will bedescribed below. In order to exhibit favorable properties, the liquidcrystal composition of the present invention preferably contains atleast one of the compounds represented by the general formula (1) in atotal amount of 0.1 to 99.9% by weight.

[0046] More specifically, the liquid crystal composition of the presentinvention comprises a first component containing at least one of thecompounds represented by general formula (1) and a second componentcomprising a compound selected from the group of compounds representedby general formulas (2) through (12) according to the purpose of theliquid crystal composition.

[0047] Among the compounds represented by general formulas (2) through(4), compounds represented by the following general formulas (2-1)through (4-24) are particularly preferred, where R² and Y² have the samemeanings as described above:

[0048] The compounds represented by general formulas (2) through (4) arecompounds having positive values of dielectric anisotropy, and excellentthermal and chemical stability, and are particularly useful forpreparing liquid crystal compositions for TFT (AM-LCD) displays whichrequire high reliability; for example, a high voltage holding ratio orhigh specific resistance.

[0049] In preparing a liquid crystal composition for TFT displays, thecompounds represented by general formulas (2) through (4) may becontained in a total amount of 0.1 to 99.9% by weight, preferably 10 to97% by weight, and more preferably 40 to 95% by weight. In this case,compounds represented by general formulas (7) through (9) maybe furtheradded for the adjustment of viscosity.

[0050] In preparing a liquid crystal composition for STN or TN displays,the compounds represented by general formulas (2) through (4) can alsobe used. Since the compounds represented by general formulas (2) through(4) have a weaker effect in lowering the threshold voltage of the liquidcrystal composition than do the compounds represented by generalformulas (5) and (6), the compounds represented by general formulas (2)through (4) are preferably contained in a total amount of 50% by weightor less.

[0051] Among the compounds represented by general formulas (5) and (6)are compounds represented by the following general formulas (5-1)through (6-3) are particular preferred; where, R³, R⁴ and Y³ have thesame meanings as described above.

[0052] The compounds represented by general formulas (5) and (6) havelarge positive values of dielectric anisotropy, and are particularlyuseful for lowering the threshold voltage of liquid crystalcompositions. These compounds are also used for expanding the nematicrange such as for adjusting values of refractive index anisotropy andelevating clearing points. Furthermore, these compounds are used forimproving the steepness of the V-T (voltage-transmissivity) curve ofliquid crystal compositions for STN or TN displays.

[0053] The compounds represented by general formulas (5) and (6) areparticularly useful for preparing liquid crystal compositions for STN orTN displays.

[0054] Increasing the quantity of the compounds represented by generalformulas (5) and (6) has the effect of lowering the threshold voltage ofthe liquid crystal composition and increasing its viscosity. Therefore,use of a large amount of these compounds is advantageous for producingdisplay element having low driving voltage, so long as the viscosity ofthe liquid crystal composition satisfies requirements. In preparingliquid crystal compositions for STN or TN displays, the total content ofthe compounds represented by general formulas (5) and (6) may be 0.1 and99.9% by weight, preferably 10 to 97% by weight, and more preferably 40to 95% by weight.

[0055] Among the compounds represented by general formulas (7) through(9), compounds represented by the following general formulas (7-1)through (9-6) are particularly preferred: where, R⁵ and R⁶ have the samemeanings as described above.

[0056] The compounds represented by general formulas (7) through (9)have small absolute values of dielectric anisotropy, and are nearlyneutral. The compounds represented by the general formula (7) are mainlyused for adjusting the viscosity or refractive index of anisotropy ofliquid crystal compositions. The compounds represented by the generalformulas (8) and (9) are used for expanding the nematic range by, forexample, elevating the clearing point of liquid crystal composition, orfor adjusting the refractive index of anisotropy.

[0057] Increase in the content of the compounds represented by generalformulas (7) through (9) has the effects of increasing the thresholdvoltage and decreasing the viscosity of liquid crystal compositions.Therefore, these compounds are preferably used in a large amount, solong as the threshold voltage of liquid crystal compositions satisfyrequirements.

[0058] When a liquid crystal composition for TFT displays is prepared,the content of the compounds represented by general formulas (7) through(9) is preferably 40% by weight or less, more preferably 35% by weightor less with respect to the liquid crystal composition. When a liquidcrystal composition for STN or TN displays is prepared, the content ofthe compounds represented by general formulas (7) through (9) ispreferably 70% by weight or less, more preferably 60% by weight or lesswith respect to the entirety of the liquid crystal composition.

[0059] Among the compounds represented by general formulas (10) through(12), compounds represented by the following general formulas (10-1)through (12-3) are particularly preferred; where, R⁷ and R⁸ have thesame meanings as described above.

[0060] The compounds represented by general formulas (10) through (12)have negative values of dielectric anisotropy. The compounds representedby the general formula (10) are two-ring compounds, and are mainly usedfor adjusting threshold voltage, viscosity, and refractive index ofanisotropy. The compounds represented by general formula (11) are usedfor expanding the nemetic range; for example, for raising the clearingpoint, or for adjusting refractive index of anisotropy. The compoundsrepresented by general formula (12) are used for expanding the nemeticrange, as well as for lowering threshold voltage and increasingrefractive index of anisotropy.

[0061] Although the compounds represented by general formulas (10)through (12) are used in N-type compositions (i.e., composition having anegative value of dielectric anisotropy Δε), increase in their contenthas the effect of lowering the threshold voltage of the composition andincreasing viscosity. Therefore, these compounds are preferably used insmall amounts, so long as the threshold voltage of the liquid crystalcomposition satisfies requirements. However, since these compounds haveabsolute values of dielectric anisotropy of 5 or smaller, attaining alow driving voltage may become impossible if the content is less than40% by weight.

[0062] When an N-type liquid crystal composition for TFT displays isprepared, the total content of the compounds represented by generalformulas (10) through (12) is preferably 40% by weight or more, morepreferably 50 to 95% by weight.

[0063] The compounds represented by general formulas (10) through (12)may also be added to a P-type liquid crystal composition (i.e., acompound having a positive value of dielectric anisotropy Δε) forcontrolling the elastic modulus of the liquid crystal composition, andfor controlling the voltage-transmissivity curve (V-T curve). In such acase, the total content of the compounds represented by general formulas(10) through (12) is preferably 30% by weight or less.

[0064] In the liquid crystal composition of the present invention, anoptically active compound is added so as to induce the helical structureof the liquid crystal composition for adjustment of twist angle andprevention of reverse twist, except for special cases such as liquidcrystal compositions for OCB (optically compensated birefringence) modedisplays. Although the optically active compounds added to the liquidcrystal compositions of the present invention may be any known opticallyactive compounds used for such a purpose, preferred examples include thefollowing optically active compounds:

[0065] These optically active compounds are usually added to the liquidcrystal composition of the present invention so as to adjust the pitchof the twist. The pitch of the twist is preferably adjusted within arange of 40 to 200 μm for liquid crystal compositions for TFT and TNdisplays, and within a range of 6 to 20 μm for liquid crystalcompositions for STN displays. In the case of bistable TN-mode displays,the pitch of the twist is preferably adjusted within a range of 1.5 to 4μm. Two or more optically active compounds may be added for adjustmentof the temperature dependence of the pitch.

[0066] The liquid crystal composition of the present invention itself isprepared by conventional methods. In a typically adopted method, variouscomponents are mutually dissolved at high temperature.

[0067] The liquid crystal composition used according to the presentinvention can also be used as a liquid crystal composition forGuest-Host-mode (GH) displays by addition of merocyanine-, styryl-,azo-, azomethine-, azoxy-, quinophthalone-, anthraquinone-, ortetrazine-based dichroic colorants. It can also be used as the liquidcrystal composition for NCAP produced by the micro-encapsulation ofnematic liquid crystals, or for a Polymer Dispersed Liquid CrystalDisplay device (PDLCD) in which a three-dimensional polymer matrix isformed in liquid crystals. In addition, it can also be used as liquidcrystal compositions for Electrically Controlled Birefringence mode(ECB) or Dynamic Scattering mode (DS) liquid crystal displays.

[0068] Method for Preparation of the Compounds

[0069] The compounds represented by the general formula (1) can beprepared easily by using of typical methods for synthesizing organicchemicals. For example, the compounds can be synthesized by selectionand combination of well-known reactions described in literatures ormagazines such as Organic Synthesis, Organic Reactions and Shin ZikkenKagaku Koza. Typical routes of synthesis will be described withreference to the following reaction formulas.

[0070] In the following reaction formulas, each of MSG1 through MSG5independently represents a residual group of an organic compound; Halrepresents Cl, Br or I; ring A represents trans-1,4-cyclohexylene group,1,4-phenylene group in which one or more hydrogen on the six-member ringmay be substituted by halogen, pyrimidine-2,5-diyl group,pyridine-2,5-diyl group, 1,3-dioxane-2,5-diyl group,tetrahydropyrane-2,5-diyl group, 1,3-dithiane-2,5-diyl group ortetrahydrothiopyrane-2,5-diyl group; Q¹ represents hydrogen, an alkylgroup having 1 to 13 carbon atoms in which each of optional nonadjacentmethylene groups may be substituted by oxygen or an alkenyl group having2 to 13 carbon atoms; and p represents 0 or 1.

[0071] In order to introduce an alkenyl group into a molecule, thefollowing method can be used. That is, Wittig's reagent (12) is allowedto react with a ketone derivative or an aldehyde derivative (11) in thepresence of a base such as sodium methylate, potassium-t-butoxide(t-BuOK), and butyl lithium, in an ether-based solvent such astetrahydrofuran (abbreviated as THF) or diethyl ether to form a compound(13). When Q¹ is an alkyl group or an alkenyl group described above, atrans-type isomer (14) can be formed by isomerizing the compound (13)with a benzenesulfinate or p-toluenesulfinate.

[0072] In order to introduce an alkenyl group of a desired chain lengthin a molecule, the following method can be used. In the same manner asdescribed above, Wittig's reagent (16) is allowed to react with a ketonederivative (15) in an ether-based solvent in the presence of a base toform a compound (17). Next, the compound (17) is allowed to react with amineral acid such as hydrochloric acid or sulfuric acid, or an organicacid such as formic acid or p-toluene sulfonic acid to form an aldehydederivative (18).

[0073] Furthermore, in the same manner as described above, Wittig'sreagent (20) is allowed to react with a ketone derivative (19) in thepresence of a base to form a compound (21). Next, the compound (21) issubjected to hydrogen reduction in a toluene/Solmix mixed solvent in thepresence of a metallic catalyst such as palladium/carbon or Raneynickel, and is allowed to react with a mineral acid such as hydrochloricacid or sulfuric acid, or an organic acid such as formic acid orp-toluene sulfonic acid to form an aldehyde derivative (22) Theseprocesses may be repeated as required.

[0074] The thus-obtained aldehyde derivative (18) or aldehyde derivative(22) is subjected to the same procedures for obtaining the compound (14)from the aldehyde derivative (11) to form a compound having an alkenylgroup of a desired chain length.

[0075] In order to introduce 2,3-difluoro-1,4-phenylene group in amolecule, the following reactions can be utilized.

[0076] When 2,3-difluoro-1,4-phenylene group is introduced into abenzene derivative MSG4 at the 4-position, a difluorobenzene derivative(31) is sequentially allowed to react with n-butyl lithium or sec-butyllithium, then with zinc chloride, in an ether-based solvent such as THFand diethyl ether, and further subjected to a coupling reaction with2,3-difluoro-1-bromobenzene in the presence of a metallic catalyst ofpalladium (0) to form a compound (32).

[0077] When a 2,3-difluoro-1,4-phenylene group is introduced into theketone site of a cyclohexanone derivative having MSG4 at the 4-position,the cyclohexanone derivative (33) is allowed to react with a Grignardreagent (34) to cause a Grignard reaction, dehydrated in the presence ofan acid catalyst, and subjected to hydrogen reduction to form a compound(35).

[0078] Compounds represented by general formula (1) in which rings A¹,A² and A³ are silacyclohexane rings can be prepared by methods disclosedin Japanese Patent Application Laid Open Nos. 7-70148, 7-112990, and7-149770; that is, a method in which a silacyclohexane compound issubjected to a coupling reaction with a corresponding organic metalreagent, or a method in which a metal is allowed to react with acompound having both a corresponding silane site and a halogen site tocause reaction in which a silicon-carbon bond is formed within themolecule.

[0079] The compound (1) described in the present application can beformed by appropriate selection of the above reactions.

EXAMPLES

[0080] The present invention will be described in further detailreferring to examples; however, the present invention is by no meanslimited by these examples. The structures of compounds were identifiedby nuclear magnetic resonance spectrometry or mass spectrometry(abbreviated as MS). In these examples, M+in MS represents the molecularion peak, C represents the crystal phase, SA the smectic A phase, SB thesmectic B phase, N the nematic phase, Iso the isotropic liquid phase,and ( ) indicate the monotropic liquid crystal phase. All phasetransition temperatures are expressed in terms of ° C.

Example 1

[0081] Synthesis of2,3-difluoro-1-ethoxy-4-(trans-4-(3-butenyl)-cyclohexyl) benzene(compound (No. 8) represented by general formula (1) in which each of R¹and X¹ is hydrogen, ring A¹ is trans-1,4-cyclohexylene group, Y¹ isethoxy group, 1 is 2, and each of m and n is 0)

[0082] Step 1

[0083] Under a nitrogen flow, 141 mmol of 1-ethoxy-2,3-difluorobenzenwas dissolved in 200 ml of THF, and the resultant solution was cooled to−70° C. While the same temperature was maintained, 130 ml of sec-butyllithium (1.3 M, cyclohexane solution) was added dropwise, and theresultant solution was stirred for 1 hour at the same temperature. Asolution of 128 mmol of 1,4-cyclohexanedione monoethlylene acetaldissolved in 200 ml of THF was added dropwise while the same temperaturewas maintained, and the resultant solution was further stirred for 1hour at the same temperature. The reaction temperature was thengradually elevated to room temperature, after which the solution wasstirred for 2 hours at room temperature. The reaction was terminated bygradual addition of the reaction mixture into 500 ml of water. The waterlayer was extracted by 500 ml of toluene, and the organic layer waswashed with 500 ml of water three times and dried over anhydrousmagnesium sulfate. The solvent was distilled off under reduced pressure,the residue was dissolved in 300 ml of toluene, 1.5 g ofp-toluenesulfonic acid monohydride was added, and the solution washeated to reflux for 1 hour. The organic layer was washed three timeswith 300 ml of water, and dried over anhydrous magnesium sulfate. Thesolvent was distilled off under reduced pressure, the residue wassubjected to silica gel column chromatography (eluent: a mixed solventof ethyl acetate/toluene=3/7), and the solvent was distilled off underreduced pressure. The residue was dissolved in 200 ml of a mixed solventof toluene/ethanol (1/1), 4.0 g of 5-wt %-palladium/carbon catalyst, andthe solution was stirred for 6 hours at room temperature under ahydrogen pressure of 1-2 kg/cm². After the catalyst was filtered off,the solvent was distilled off from the filtrate under reduced pressure,the residue was subjected to silica gel column chromatography (eluent:ethyl acetate/toluene=3/7), and the solvent was distilled off underreduced pressure, to form crude4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexane monoethylene acetal.

[0084] Step 2

[0085] Crude 4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexanone monoethyleneacetal (50.3 mmol) obtained in Step 1 was dissolved in 200 ml oftoluene, 87% formic acid (503 mmol) was added, and the solution washeated to reflux for 4 hours. The reaction solution was washed twicewith 100 ml of a saturated aqueous solution of sodium hydrogencarbonate, then three times with 100 ml of water, and dried overanhydrous magnesium sulfate. The solvent was distilled off under reducedpressure, to form crude 4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexanone(50.3 mmol).

[0086] Step 3

[0087] A mixture of 2-(1,3-dioxane-2-yl)-ethyltriphenyl phosphoniumbromide (60.4 mmol) and 30 ml of THF was cooled down to −30° C. by useof a refrigerant under a nitrogen flow. To this mixture, t-BuOK (60.4mmol) was added, and the mixture was stirred for one hour. A solution ofthe crude 4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexanone (50.3 mmol)dissolved in 100 ml of THF was added dropwise to this mixture whiletemperature was maintained at −30° C. or below. After completion of theaddition, the reaction temperature was gradually elevated to roomtemperature, and the mixture was stirred for 2 hours. The reactionmixture was filtered with celite, the solvent was distilled off underreduced pressure, the residue was subjected to silica gel columnchromatography (eluent: a mixed solvent of ethyl acetate/toluene=3/7),the solvent was distilled off under reduced pressure, and the productwas re-crystallized from heptane to form2-(2-(4-(2,3-difluoro-4-ethoxyphenyl)cyclohexylidene)-ethyl)-1,3-dioxane(36.9 mmol).

[0088] Step 4

[0089] The2-(2-(4-(2,3-difluoro-4-ethoxyphenyl)cyclohexylidene)-ethyl)-1,3-dioxane(36.9 mmol) obtained by the reaction of Step 3 was dissolved in 100 mlof a mixed solvent of toluene/ethanol (1/1), 4.0 g of 5-wt%-palladium/carbon catalyst was added, and the solution was stirred for7 hours at room temperature under a hydrogen pressure of 1-2 kg/cm².After the catalyst was filtered off, the solvent was distilled off fromthe filtrate under reduced pressure, the residue was subjected to silicagel column chromatography (eluent: a mixed solvent of ethylacetate/toluene=3/7), the solvent was distilled off under reducedpressure, and the product was re-crystallized from ethanol to form2-(2-(trans-4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexyl)-ethyl)-1,3-dioxane(36.9 mmol).

[0090] Step 5

[0091] The2-(2-(trans-4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexyl)-ethyl)-1,3-dioxane(19.8 mmol) obtained by the reaction of Step 4 was dissolved in 100 mlof toluene, 87% formic acid (198 mmol) was added, and the solution washeated to reflux for 4 hours. The reaction solution was twice washedwith 50 ml of a saturated aqueous solution of sodium hydrogen carbonate,then three times with 50 ml of water, and dried over anhydrous magnesiumsulfate. The solvent was distilled off under reduced pressure, to formcrude 3-(trans-4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexyl)-propanal(19.8 mmol).

[0092] Step 6

[0093] A mixture of methyltriphenyl phosphonium bromide (23.8 mmol) and50 ml of THF was cooled to −30° C. by use of a refrigerant under anitrogen flow. To this mixture, t-BuOK (23.8 mmol) was added and themixture was stirred for one hour. A solution of the crude3-(trans-4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexyl)-propanal (19.8mmol) and dissolved in 50 ml of THF was added dropwise to this mixturewhile temperature was maintained at −30° C. or below. After the additionwas completed, the reaction temperature was gradually elevated to roomtemperature, and the mixture was stirred for 2 additional hours. Thereaction mixture was filtered with celite, the solvent was distilled offunder reduced pressure, the residue was subjected to silica gel columnchromatography (eluent: a mixed solvent of ethyl acetate/heptane 1/1),the solvent was distilled off under reduced pressure, and the productwas re-crystallized from ethanol to form the target compound (9.51mmol).

[0094] Various spectra confirmed the structure of this product.

[0095] MS:m/e=294 (M⁺)

[0096] Phase transition temperature: C 39.4 Iso

[0097] In the similar processes as with Example 1, the followingcompounds can be prepared. compound NO.1

compound NO.2

compound NO.3

C 34.0 Iso(° C.) compound NO.4

compound NO.5

compound NO.6

C 40.8 Iso(° C.) compound NO.7

compound NO.8

C 39.4 Iso(° C.) compound NO.9

compound NO.10

compound NO.11

C 27.1 Iso(° C.) compound NO.12

compound NO.13

C 22.7 Iso(° C.) compound NO.14

compound NO.15

compound NO.16

compound NO.17

compound NO.18

compound NO.19

compound NO.20

compound NO.21

compound NO.22

compound No.23

compound NO.24

compound No.25

compound NO.26

compound No.27

compound NO.28

compound NO.29

compound NO.30

compound NO.31

C 86.7 N 162.8 Iso(° C.) compound NO.32

compound NO.33

C 76.8 (S_(B) 62.0) N 172.0 Iso(° C.) compound NO.34

compound NO.35

compound NO.36

C 80.6 N 169.2 Iso(° C.) compound NO.37

compound NO.38

C 80.0 (S_(B) 71.8) N 184.8 Iso(° C.) compound NO.39

compound NO.40

compound NO.41

compound NO.42

compound NO.43

C55.7 S_(B) 98.3 N 172.5 Iso(° C.) compound NO.44

compound NO.45

compound NO.46

C 42.6 N 145.5 Iso(° C.) compound NO.47

compound NO.48

compound NO.49

compound NO.50

compound NO.51

compound NO.52

compound NO.53

compound NO.54

compound NO.55

compound NO.56

compound NO.57

compound NO.58

compound NO.59

compound NO.60

compound NO.61

compound NO.62

compound NO.63

compound NO.64

compound NO.65

compound NO.66

compound NO.67

compound NO.68

compound NO.69

compound NO.70

compound NO.71

compound NO.72

compound NO.73

compound NO.74

compound NO.75

compound NO.76

compound NO.77

compound NO.78

compound NO.79

compound NO.80

compound NO.81

compound NO.82

compound NO.83

compound NO.84

compound NO.85

compound NO.86

compound NO.87

compound NO.88

compound NO.89

compound NO.90

compound NO.91

compound NO.92

compound NO.93

compound NO.94

compound NO.95

compound NO.96

compound NO.97

compound NO.98

compound NO.99

compound NO.100

compound NO.101

compound NO.102

compound NO.103

compound NO.104

compound NO.105

compound NO.106

compound NO.107

compound NO.108

compound NO.109

compound NO.110

compound NO.111

compound NO.112

compound NO.113

compound No.114

compound NO.115

compound NO.116

compound NO.117

compound No.118

compound NO.119

compound NO.120

compound NO.121

compound NO.122

compound NO.123

compound NO.124

compound NO.125

compound NO.126

compound NO.127

compound NO.128

compound NO.129

compound NO.130

compound NO.131

compound NO.132

compound NO.133

compound NO.134

compound NO.135

compound NO.136

compound NO.137

compound NO.138

compound NO.139

compound NO.140

compound NO.141

compound NO.142

compound NO.143

compound NO.144

compound NO.145

compound NO.146

compound NO.147

compound NO.148

compound NO.149

compound NO.150

compound NO.151

compound NO.152

compound NO.153

compound NO.154

Compound NO.155

compound NO.156

compound NO.157

compound NO.158

compound NO.159

compound NO.160

compound NO.161

compound NO.162

compound NO.163

compound NO.164

compound NO.165

compound NO.166

compound NO.167

compound NO.168

compound NO.169

compound NO.170

compound NO.171

compound NO.172

compound NO.173

compound NO.174

compound NO.175

compound NO.176

compound NO.177

compound NO.178

compound NO.179

compound NO.180

compound NO.181

compound NO.182

compound NO.183

compound NO.184

compound NO.185

compound NO.186

compound NO.187

compound NO.188

compound NO.189

compound NO.190

compound NO.191

compound NO.192

compound NO.193

compound NO.194

compound NO.195

compound NO.196

compound NO.197

compound NO.198

compound NO.199

compound NO.200

compound NO.201

compound NO.202

compound NO.203

compound NO.204

compound NO.205

compound NO.206

compound NO.207

compound NO.208

compound NO.209

compound NO.210

compound No.211

compound NO.212

compound NO.213

compound NO.214

compound NO.215

compound NO.216

compound NO.217

compound NO.218

compound NO.219

compound NO.220

compound NO.221

compound NO.222

compound NO.223

compound NO.224

compound NO.225

compound NO.226

compound NO.227

compound NO.228

compound NO.229

compound NO.230

compound NO.231

compound NO.232

compound NO.233

compound NO.234

compound NO.235

compound NO.236

compound NO.237

compound NO.238

compound No.239

compound NO.240

compound NO.241

compound NO.242

compound No.243

compound NO.244

compound NO.245

compound NO.246

compound NO.247

compound NO.248

compound NO.249

compound NO.250

compound NO.251

compound NO.252

compound NO.253

compound NO.254

compound NO.255

compound NO.256

compound NO.257

compound NO.258

compound NO.259

compound NO.260

compound NO.261

compound NO.262

compound NO.263

compound NO.264

compound NO.265

compound NO.266

compound NO.267

compound NO.268

compound NO.269

compound NO.270

compound NO.271

compound NO.272

compound NO.273

compound NO.274

compound NO.275

compound NO.276

compound NO.277

compound NO.278

compound NO.279

compound NO.280

compound NO.281

compound NO.282

compound NO.283

compound NO.284

compound NO.285

compound NO.286

compound NO.287

compound NO.288

compound NO.289

compound NO.290

compound NO.291

compound NO.292

compound NO.293

compound NO.294

compound NO.295

compound NO.296

compound NO.297

compound NO.298

compound NO.299

compound NO.300

compound NO.301

C 50.44 Iso(° C.) compound NO.302

compound NO.303

compound NO.304

compound NO.305

compound NO.306

compound NO.307

compound NO.308

compound NO.309

compound NO.310

compound NO.311

compound NO.312

compound NO.313

compound NO.314

compound NO.315

[0098] Examples of nematic liquid crystal compositions containingExamples of nematic liquid crystal compositions containing the liquidcrystalline compounds of the present invention are shown below. In theseexample compositions, the notations of the compounds follow thedefinitions shown in Table 1, and their proportions are shown in termsof percent by weight.

[0099] Viscosity (η) was measured at 20.0° C., and refraction index ofanisotropy (Δn), value of dielectric anisotropy (Δε), threshold voltage(Vth), and twist pitch (P) were measured at 25.0° C.

[0100] Neither appearance of the symectic phase nor precipitation ofcrystals was observed in any of the following compounds, even after thecompounds were allowed to stand for 40 days in a freezer at atemperature of −20° C. TABLE 1 Description method of compounds usingmarks.

1) Left end groups R— Marks C_(n)H_(2n+1)— n- C_(n)H_(2n+1)O— nO—C_(n)H_(2n+1)OC_(m)H_(2m—) nOm- CH₂═CH— V- CH₂═CHC_(n)H_(2n)— Vn-C_(n)H_(2n+1)CH═CHC_(m)H_(2m)— nVm-C_(n)H_(2n+1)CH═CHC_(m)H_(2m)CH═CHC_(k)H_(2k)— nVmVk- CF₂═CH— VFF- 2)Ring structurez —(A₁)—, —(A_(n))— Marks

B

B(F)

B(2F)

B(2F,3F)

B(2F,5F)

B(2CN,3CN)

B(F,F)

H

Py

Pr(F) 3) Bonding groups —Z₁—, —Z_(n)— Marks —C₂H₄ 2 —C₄H₈— 4 —COO— E—C≡C— T —CH═CH— V —CF₂O— CF2O —OCF₂— OCF2 4) Right end groups —X— Marks—F —F —Cl —CL —CN —C —CF₃ —CF3 —OCF₃ —OCF3 —OCF₂H —OCF2H —C_(n)H_(2n+1)—n —OC_(n)H_(2n+1) —On —COOCH₃ —EMe —C_(n)H_(2n)CH═CH₂ -n V—C_(m)H_(2m)CH═CHC_(n)H_(2n+1) -mVn —C_(m)H_(2m)CH═CHC_(n)H_(2n)F -mVnF—CH═CF₂ -VFF —C_(n)H_(2n)CH═CF₂ -nVFF 5) Examples of description Example1 3-H2B(F,F)B(F)-F

Example 2 3-HB(F)TB-2

Example 3 1V2-BEB(F,F)-C

Example 2 Composition Example 1

[0101] V-HB(2F,3F)-O2 (No. 6) 15.0% 3-HEB-O2 12.9% 3-HEB-O4 20.7%4-HEB-O2 15.5% 5-HEB-O1 15.5% 3-HEB-O2 10.4% T_(NI) = 60.0 (° C.) η =20.0 (mPa · C.) Δn = 0.085 Δε = −2.0

Example 3 Composition Example 2

[0102] V2-HB(2F,3F)-O2 (No. 8) 15.0% 3-HEB-O2 12.9% 3-HEB-O4 20.7%4-HEB-O2 15.5% 5-HEB-O1 3-HEB-O2 10.4% T_(NI) = 64.0 (° C.) η = 20.1(mPa · s) Δn = 0.086 Δε = −2.1

Example 4 Composition Example 3

[0103] V-HB(2F,3F)-O3 (No. 11) 15.0% 3-HEB-O2 12.9% 3-HEB-O4 20.7%4-HEB-O2 15.5% 5-HEB-O1 15.5% 3-HEB-O2 10.4% T_(NI) = 58.6 (° C.) η =20.1 (mPa · s) Δn = 0.082 Δε = −2.0

Example 5 Composition Example 4

[0104] V-HHB(2F,3F)-O1 (No. 31) 15.0% 3-HEB-O2 12.9% 3-HEB-O4 20.7%4-HEB-O2 15.5% 5-HEB-O1 15.5% 3-HEB-O2 10.4% T_(NI) = 82.1 (° C.) η =22.4 (mPa · s) Δn = 0.090 Δε = −2.1

Example 6 Composition Example 5

[0105] V2-HHB(2F,3F)-O1 (No. 33) 15.0% 3-HEB-O2 12.9% 3-HEB-O4 20.7%4-HEB-O2 15.5% 5-HEB-O1 15.5% 3-HEB-O2 10.4% T_(NI) = 83.3 (° C.) η =22.0 (mpa · s) Δn = 0.089 Δε = −2.0

Example 7 Composition Example 6

[0106] V-HHB(2F,3F)-O2 (No. 36) 15.0% 3-HEB-O2 12.9% 3-HEB-O4 20.7%4-HEB-O2 15.5% 5-HEB-O1 15.5% 3-HEB-O2 10.4% T_(NI) = 84.7 (° C.) η =21.7 (mPa · s) Δn = 0.092 Δε = −2.0

Example 8 Composition Example 7

[0107] V2-HHB(2F,3F)-O2 (No. 38) 15.0% 3-HEB-O2 12.9% 3-HEB-O4 20.7%4-HEB-O2 15.5% 5-HEB-O1 15.5% 3-HEB-O2 10.4% T_(NI) = 87.1 (° C.) η =21.4 (mPa · s) Δn = 0.092 Δε = −1.7

Example 9 Composition Example 8

[0108] VFF-HB(2F,3F)-O2 (No. 196) 15.0% 3-HEB-O2 12.9% 3-HEB-O4 20.7%4-HEB-O2 15.5% 5-HEB-O1 15.5% 3-HEB-O2 10.4% T_(NI) = 62.0 (° C.) η =21.3 (mpa · s) Δn = 0.084 Δε = −1.9

Example 10 Composition Example 9

[0109] V2-HB(2F,3F)-O2 (No. 8) 14.0% V2-HHB (2F, 3F)-O1 (No. 33) 14.0%4-HEB-O2 20.0% 5-HEB-O1 20.0% 3-HEB-O2 18.0% 5-HEB-O2 14.0% T_(NI) =79.7 (° C.) η = 22.7 (mPa · s) Δn = 0.097 Δε = −2.5

Example 11 Composition Example 10

[0110] V-HB(2F,3F)-O3 (No. 11) 8.0% V2-HB(2F,3F)-O2 (No. 8) 8.0%V2-HHB(2F,3F)-O2 (No. 38) 8.0% 3-HH-2 5.0% 3-HH-4 6.0% 3-HH-O1 4.0%3-HH-O3 5.0% 5-HH-O1 4.0% 3-HB(2F,3F)-O2 12.0% 5-HB(2F,3F)-O2 11.0%3-HHB(2F,3F)-O2 14.0% 5-HHB(2F,3F)-O2 15.0% T_(NI) = 71.7 (° C.) Δn =0.079 Δε = −4.4

Example 12 Composition Example 11

[0111] V-HHB(2F,3F)-O1 (No. 31) 4.0% V-HHB(2F,3F)-O2 (No. 36) 4.0%3-HH-4 5.0% 3-HH-5 5.0% 3-HH-O1 6.0% 3-HH-O3 6.0% 3-HB-O1 5.0% 3-HB-O25.0% 3-HB(2F,3F)-O2 10.0% 5-HB(2F,3F)-O2 10.0% 3-HHB(2F,3F)-O2 12.0%5-HHB(2F,3F)-O2 13.0% 3-HHEH-3 5.0% 3-HHEH-5 5.0% 4-HHEH-3 5.0% T_(NI) =89.1 (° C). Δn = 0.079 Δε = −3.3

Example 13 Composition Example 12

[0112] V-HHB(2F,3F)-O1 (No. 31) 4.0% 3-BB(2F,3F)-O2 12.0% 3-BB(2F,3F)-O410.0% 5-BB(2F,3F)-O4 10.0% 2-BB(2F,3F)B-3 25.0% 3-BB(2F,3F)B-5 13.0%5-BB(2F,3F)B-5 14.0% 5-BB(2F,3F)B-7 12.0% T_(NI) = 73.9 (° C.) Δn =0.194 Δε = −3.5

Example 14 Composition Example 13

[0113] V-HB(2F,3F)-O2 (No. 6) 6.0% 3-BB(2F,3F)-O2 10.0% 5-BB-5 9.0%5-BB-O6 9.0% 5-BB-O8 8.0% 3-BEB-5 6.0% 5-BEB-5 3.0% 3-HEB-O2 20.0%5-BBB(2F,3F)-7 9.0% 3-H2BB(2F)-5 20.0% T_(NI) = 71.6 (° C.) Δn = 0.146Δε = −3.3

Example 15 Composition Example 14

[0114] V-HB(2F,3F)-O3 (No. 11) 5.0% V2-HB(2F,3F)-O2 (No. 8) 5.0%V-HHB(2F,3F)-O2 (No. 36) 5.0% 3-HB-O2 6.0% 3-HEB(2F,3F)-O2 9.0%4-HEB(2F,3F)-O2 9.0% 5-HEB(2F,3F)-O2 9.0% 2-BB2B-O2 6.0% 3-BB2B-O2 6.0%5-BB2B-O1 6.0% 5-BB2B-O2 6.0% 1-B2BB(2F)-5 7.0% 3-B2BB(2F)-5 7.0%5-B(F)BB-O2 7.0% 3-BB(2F,3F)B-3 7.0% T_(NI) = 81.6 (° C.) η = 29.0 (mPa· s) Δn = 0.162 Δε = −2.7

Example 16 Composition Example 15

[0115] V2-HB(2F,3F)-O2 (No. 8) 9.0% V-HHB(2F,3F)-O2 (No. 36) 9.0%3-HB-O2 9.0% 2-BTB-O1 5.0% 1-BTB-O2 5.0% 3-BTB(2F,3F)-O2 13.0%5-BTB(2F,3F)-O2 13.0% 3-B(2F,3F)TB(2F,3F)-O4 4.0% 5-B(2F,3F)TB(2F,3F)-O44.0% 3-HBTB-O1 5.0% 3-HBTB-O2 5.0% 3-HBTB-O3 5.0% 3-HHB(2F,3F)-O2 6.0%5-HBB(2F,3F)-O2 5.0% 5-BPr(F)-O2 3.0% T_(NI) = 95.0 (° C.) η = 30.2 (mpa· s) Δn = 0.223

Example 17 Composition Example 16

[0116] V-HB(2F,3F)-O3 (No. 11) 10.0% V2-HB(2F,3F)-O2 (No. 8) 6.0%V-HHB(2F,3F)-O1 (No. 31) 5.0% V2-HHB(2F,3F)-O1 (No. 33) 6.0%V2-HHB(2F,3F)-O2 (No. 38) 6.0% 3-HB-O2 4.0% 5-HB-3 8.0% 5-BB(2F,3F)-O210.0% 5-HB(2F,3F)-O2 8.0% 5-HHB(2F,3F)-O2 4.0% 5-HHB(2F,3F)-1O1 4.0%3-HHB(2F,3F)-1 5.0% 3-HBB-2 6.0% 3-BB(2F,3F)B-3 8.0% 5-B2BB(2F,3F)-O210.0% T_(NI) = 72.3 (° C.) Δn = 0.128 Δε = −4.2

Example 18 Composition Example 17

[0117] V-HB(2F,3F)-O2 (No. 6) 9.0% V-HHB(2F,3F)-O2 (No. 36) 3.0%V2-HHB(2F,3F)-O1 (No. 33) 3.0% V2-HHB(2F,3F)-O2 (No. 38) 7.0% 3-HB-O220.0% 1O1-HH-3 6.0% 1O1-HH-5 5.0% 3-HH-EMe 12.0% 5-HEB-O1 8.0% 3-HHB-16.0% 3-HHB-3 6.0% 3-HEB(2CN,3CN)-O5 4.0% 4-HEB(2CN,3CN)-O5 3.0%5-HEB(2CN,3CN)-O5 2.0% 2-HBEB(2CN,3CN)-O2 2.0% 4-HBEB(2CN,3CN)-O4 4.0%T_(NI) = 75.8 (° C.) η = 33.2 (mPa · s) Δn = 0.087 Δε = −6.3

Example 19 Composition Example 18

[0118] V-HB(2F,3F)-O2 (No. 6) 5.0% V2-HHB(2F,3F)-O2 (No. 38) 3.0%1V2-BEB(F,F)-C 5.0% 3-HB-C 20.0% V2-HB-C 6.0% 2-BTB-1 10.0% 1O1-HH-33.0% 3-HH-4 11.0% 3-HHB-1 11.0% 3-H2BTB-2 4.0% 3-H2BTB-3 4.0% 3-H2BTB-44.0% 3-HB(F)TB-2 6.0% 3-HB(F)TB-3 5.0% 3-HHB-C 3.0% T_(NI) = 89.0 (° C.)η = 17.3 (mPa · s) Δn = 0.154 Δε = 6.7 V_(th) = 2.19 (V)

[0119] The pitch of the composition produced by adding 0.8 part byweight of an optically active compound CM33 to 100 parts by weight ofthe above composition was, P=11.3 μm.

Example 20 Composition Example 19

[0120] V-HHB(2F,3F)-O1 (No. 31) 3.0% V-HHB(2F,3F)-O2 (No. 36) 3.0%2O1-BEB(F)-C 5.0% 3O1-BEB(F)-C 12.0% 5O1-BEB(F)-C 4.0% 1V2-BEB(F,F)-C10.0% 3-HEB-O4 4.0% 3-HH-EMe 6.0% 3-HB-O2 18.0% 7-HEB-F 2.0% 7-HHEB-F2.0% 5-HHEB-F 2.0% 3-HBEB-F 4.0% 2O1-HBEB(F)-C 2.0% 3-HB(F)EB(F)-C 2.0%3-HBEB(F,F)-C 2.0% 3-HHB-F 4.0% 3-HHB-O1 4.0% 3-HHB-3 3.0% 3-HEBEB-F2.0% 3-HEBEB-1 2.0% 3-HHB(F)-C 4.0% T_(NI) = 76.4 (° C.) η = 38.0 (mPa ·s) Δn = 0.117 Δε = 23.9 V_(th) = 1.12 (V)

Example 21 Composition Example 20

[0121] V-HB(2F,3F)-O2 (No. 6) 5.0% V-HB(2F,3F)-O3 (No. 11) 5.0%V-HHB(2F,3F)-O1 (No. 31) 4.0% V2-HHB(2F,3F)-O1 (No. 33) 4.0%1V2-BEB(F,F)-C 6.0% 3-HB-C 18.0% 2-BTB-1 10. 0% 5-HH-VFF 20.0% 1-BHH-VFF8.0% 1-BHH-2VFF 11.0% 3-H2BTB-2 5.0% 3-HHB-1 4.0% T_(NI) = 71.8 (° C.) η= 16.8 (mPa · s) Δn = 0.123 Δε = 5.3 V_(th) = 2.51 (V)

Example 22 Composition Example 21

[0122] V2-HHB(2F,3F)-O2 (No. 38) 10.0% 5-HB-F 12.0% 6-HB-F 9.0% 7-HB-F7.0% 2-HHB-OCF3 7.0% 3-HRB-OCF3 7.0% 4-HHB-OCF3 7.0% 5-HHB-OCF3 5.0%3-HH2B-OCF3 4.0% 5-HH2B-OCF3 4.0% 3-HHB(F,F)-OCF3 5.0% 3-HBB(F)-F 10.0%3-HH2B(F)-F 3.0% 3-HB(F) BH-3 3.0% 5-HBBH-3 3.0% 3-HHB(F,F)-OCF2H 4.0%T_(NI) = 92.1 (° C.) η = 15.8 (mPa · s) Δn = 0.091 Δε = 3.3 V_(th) =2.73 (V)

Example 23 Composition Example 22

[0123] V-HHB(2F,3F)-O2 (No. 36) 5.0% 7-HB(F,F)-F 5.0% 3-H2HB(F,F)-F12.0% 4-H2HB(F,F)-F 6.0% 3-HHB(F,F)-F 10.0% 3-HBB(F,F)-F 10.0%3-HHEB(F,F)-F 10.0% 4-HHEB(F,F)-F 3.0% 5-HHEB(F,F)-F 3.0% 2-HBEB(F,F)-F3.0% 3-HBEB(F,F)-F 5.0% 5-HBEB(F,F)-F 3.0% 3-HGB(F,F)-F 15.0%3-HBCF2OB(F,F)-F 4.0% 3-HHBB(F,F)-F 6.0% T_(NI) = 80.1 (° C.) η = 33.6(mPa · s) Δn = 0.087 Δε = 12.8 V_(th) = 1.51 (V)

[0124] The pitch of the composition produced by adding 0.3 part byweight of an optically active compound CN to 100 parts by weight of theabove composition was, P=77.0 μm.

Example 24 Composition Example 23

[0125] V-HHB(2F,3F)-O1 (No. 31) 5.0% V2-HHB(2F,3F)-O1 (No. 33) 5.0%2-HHB(F)-F 2.0% 3-HHB(F)-F 2.0% 5-HHB(F)-F 2.0% 2-HBB(F)-F 6.0%3-HBB(F)-F 6.0% 2-H2BB(F)-F 9.0% 3-H2BB(F)-F 9.0% 3-HBB(F,F)-F 25.0%5-HBB(F,F)-F 19.0% 1O1-HBBH-4 5.0% 1O1-HBBH-5 5.0% T_(NI) = 101.0 (° C.)η = 35.8 (mPa · s) Δn = 0.134 Δε = 6.1 V_(th) = 2.17 (V)

[0126] The pitch of the composition produced by adding 0.2 part byweight of an optically active compound CM43L to 100 parts by weight ofthe above composition was, P=77.7 μm.

Example 25 Composition Example 24

[0127] V-HB(2F,3F)-O3 (No. 11) 15.0% V2-HB(2F,3F)-O2 (No. 8) 15.0%V-HHB(2F,3F)-O1 (No. 31) 10.0% V2-HHB(2F,3F)-O1 (No. 33) 10.0%V2-HHB(2F,3F)-O2 (No. 38) 10.0% 3-HH-EMe 25.0% 5-HH-EMe 15.0%

Example 26 Composition Example 25

[0128] V-HB(2F,3F)-O3 (No. 11) 13.0% V2-HB(2F,3F)-O2 (No. 8) 13.0%V2-HHB(2F,3F)-O1 (No. 33) 10.0% V2-HHB(2F,3F)-O2 (No. 38) 10.0% 3-HH-EMe20.0% 5-HH-EMe 10.0% 3-HH-4 10.0% 3-HB-O2 5.0% 3-HHB-1 9.0%

Example 27 Composition Example 26

[0129] V-HB(2F,3F)-O3 (No. 11) 12.0% V2-HB(2F,3F)-O2 (No. 8) 12.0%V-HHB(2F,3F)-O2 (No. 31) 8.0% V2-HHB(2F,3F)-O1 (No. 33) 8.0% 3-HH-EMe12.0% 5-HH-EMe 5.0% 3-HEB-O2 6.0% 3-HEB-O4 8.0% 4-HEB-O2 6.0% 5-HEB-O16.0% 5-HEB-O2 4.0% 3-HHB-1 13.0%

INDUSTRIAL APPLICABILITY

[0130] As seen from the above examples, the compound of the presentinvention which has two to four rings with containing an alkenyl groupand 2,3-difluorophenyl group, has the following features:

[0131] 1) Exhibits a wide liquid crystal phase temperature range, aswell as frequent appearance of the nematic phase;

[0132] 2) Significantly improves response speeds and lowers drivingvoltages in IPS and VA systems because of large negative Δε and lowviscosity;

[0133] 3) Increases K₃₃/K₁₁ values and decreases Δε/ε⊥, improving thesteepness of the V-T curve in the STN system; and

[0134] 4) Stable nematic liquid crystal compositions can be preparedtherefrom without the precipitation of crystals or the appearance of thesmectic phase even at extremely low temperature.

[0135] The compound of the present invention exhibits the above

1. A liquid crystalline compound represented by the following generalformula (1):

where, R¹ represents hydrogen, fluorine, an alkyl group having 1 to 15carbon atoms or an alkenyl group having 2 to 15 carbon atoms; each ofrings A¹, A² and A³ independently represents trans-1,4-cyclohexylenegroup, 1,4-cyclohexenylene group, trans-1,4-silacyclohexylene group,1,4-phenylene group, 2,3-difluoro-1,4-phenylene group,2-fluoro-1,4-phenylene group, 3-fluoro-1,4-phenylene group,pyrimidine-2,5-diyl group, pyridine-2,5-diyl group, 1,3-dioxane-2,5-diylgroup, tetrahydropyrane-2,5-diyl group, 1,3-dithiane-2,5-diyl group ortetrahydrothiopyrane-2,5-diyl group; X¹ represents hydrogen or fluorine;Y¹ represents hydrogen or an alkyl group having 1 to 15 carbon atoms, inwhich each of optional nonadjacent methylene groups (—CH₂—) may besubstituted by oxygen; 1 represents an integer from 1 to 10; in whicheach of optional nonadjacent methylene groups in (—CH₂—), may besubstituted by oxygen; and each of m and n independently represents 0or
 1. 2. A liquid crystalline compound according to claim 1, wherein thering A₁ in general formula (1) is trans-1,4-cyclohexylene group and mand n are both
 0. 3. A liquid crystalline compound according to claim 1,wherein each of the rings A¹ and A² in general formula (1) isindependently trans-1,4-cyclohexylene group, 2,3-difluoro-1,4-phenylenegroup or 1,3-dioxane-2,5-diyl group; m is 1; and n is
 0. 4. A liquidcrystalline compound according to claim 1, wherein each of the rings A¹,A² and A³ in general formula (1) is independentlytrans-1,4-cyclohexylene group, 2,3-difluoro-1,4-phenylene group or1,3-dioxane-2,5-diyl group; and m and n are both
 1. 5. A liquid crystalcomposition comprising at least two components, characterized bycontaining at least one liquid crystalline compound represented bygeneral formula (1).
 6. A liquid crystal composition comprising at leastone liquid crystalline compound according to any one of claims 1 through4 as a first component and at least one compound selected from a groupconsisting of compounds represented by general formulas (2), (3) and (4)as a second component,

where R² represents an alkyl group having 1 to 10 carbon atoms, in whicheach of optional nonadjacent methylene groups may be substituted byoxygen or —CH═CH— group, and in which each of optional hydrogen in thesemethylene groups may be substituted by fluorine; Y² represents fluorine,chlorine, —OCF₃, —OCF₂H, —CF₃, —CF₂H, —CFH₂, —OCF₂CF₂H or —OCF₂CFHCF₃;each of L¹ and L² independently represents hydrogen or fluorine; each ofZ¹ and Z² independently represents 1,2-ethylene group, vinylene group,1,4-butylene group, —COO—, —CF₂O—, —OCF₂— or a single bond; ring Brepresents trans-1,4-cyclohexylene group, 1,3-dioxane-2,5-diyl group or1,4-phenylene group, in which each of hydrogen may be substituted byfluorine; and ring C represents trans-1,4-cyclohexylene group or1,4-phenylene group, in which each of hydrogen may be substituted byfluorine.
 7. A liquid crystal composition comprising at least oneliquid: crystalline compound according to any one of claims 1 through 4as a first component, and at least one compound selected from a groupconsisting of compounds represented by general formulas (5) and (6) as asecond component,

where each of R³ and R⁴ independently represents an alkyl group having 1to 10 carbon atoms, in which each of optional nonadjacent methylenegroups may be substituted by oxygen or vinylene group, and in which eachof optional hydrogen in these methylene groups may be substituted byfluorine; Y³ represents —CN or —C≡C—CN; ring D representstrans-1,4-cyclohexylene group, 1,4-phenylene group, pyrimidine-2,5-diylgroup or 1,3-dioxane-2,5-diyl group; ring E representstrans-1,4-cyclohexylene group or 1,4-phenylene group, in which each ofoptional hydrogen may be substituted by fluorine or, pyrimidine-2,5-diylgroup; ring F represents trans-1,4-cyclohexylene group or 1,4-phenylenegroup; Z⁵ represents 1,2-ethylene group, —COO— or a single bond; each ofL³, L⁴ and L⁵ independently represents hydrogen or fluorine; and each ofa, b and c independently represents 0 or
 1. 8. A liquid crystalcomposition comprising at least one liquid crystalline compoundaccording to any one of claims 1 through 4 as a first component and atleast one compound selected from a group consisting of compoundsrepresented by general formulas (7), (8) and (9) as a second component.

where each of R⁵ and R⁶ independently represents an alkyl group having 1to 10 carbon atoms, in which each of optional nonadjacent methylenegroups may be substituted by oxygen or vinylene group and in which eachof optional hydrogen in these methylene may be substituted by fluorine;each of rings G, I and J independently representstrans-1,4-cyclohexylene group, pyrimidine-2,5-diyl group or1,4-phenylene group in which hydrogen may be substituted by fluorine;and each of Z⁴ and Z⁵ independently represents 1,2-ethylene group,vinylene group, —COO—, —C≡C— or a single bond.
 9. A liquid crystalcomposition comprising at least one liquid crystalline compoundaccording to any one of claims 1 through 4 as a first component and atleast one compound selected from a group consisting of compoundsrepresented by general formulas (10), (11) and (12) as a secondcomponent.

where each of R⁷ and R⁸ independently represents an alkyl group having 1to 10 carbon atoms, in which each of optional nonadjacent methylenegroups may be substituted by oxygen or vinylene group, and in which eachof optional hydrogen in these methylene groups may be substituted byfluorine; each of rings K and M independently representstrans-1,4-cyclohexylene group or 1,4-phenylene group; each of L⁶ and L⁷independently represents hydrogen or fluorine, but L⁶ and L⁷ are notboth hydrogen simultaneously; and each of Z⁶ and Z⁷ independentlyrepresents —CH₂CH₂—, —CH₂O— or a single bond.
 10. A liquid crystalcomposition comprising at least one liquid crystalline compoundaccording to any one of claims 1 through 4 as a first component, atleast one compound selected from a group consisting of compoundsrepresented by general formulas (7), (8) and (9) as a second componentand at least one compound selected from a group consisting of compoundsrepresented by general formulas (10), (11) and (12) as a thirdcomponent.
 11. A liquid crystal composition comprising at least oneliquid crystalline compound according to any of claims 1 through 4 as afirst component, at least one compound selected from a group consistingof compounds represented by general formulas (2), (3) and (4) as asecond component and at least one compound selected from a groupconsisting of compounds represented by general formulas (7), (8) and (9)as a third component.
 12. A liquid crystal composition comprising atleast one liquid crystalline compound according to any of claims 1through 4 as a first component, at least one compound selected from agroup consisting of compounds represented by general formulas (5) and(6) as a second component and at least one compound selected from agroup consisting of compounds represented by general formulas (7), (8)and (9) as a third component.
 13. A liquid crystal compositioncomprising at least one liquid crystalline compound according to any ofclaims 1 through 4 as a first component, at least one compound selectedfrom a group consisting of compounds represented by general formulas(2), (3) and (4) as a second component, at least one compound selectedfrom a group consisting of compounds represented by general formulas (5)and (6) as a third component, and at least one compound selected from agroup consisting of compounds represented by general formulas (7), (8)and (9) as a fourth component.
 14. A liquid crystal compositionaccording to any of claims 5 through 13 further comprising one or moreoptically active compounds.
 15. A liquid crystal display deviceconstituted from a liquid crystal composition according to any of claims5 through 14.